All such lubricators feed oil through the drop-nipple by hydrostatic
pressure; that is, the water of condensation in the condenser and its
pipe being elevated above the oil magazine forces the oil out of the
latter by just so much pressure as the column of water is higher than
the exit or outlet of oil-nipple. The higher the column of water the
more positive will the oil feeds. As soon as the oil drop leaves the
nipple it ceases to be actuated by the hydrostatic pressure, and rises
through the water in the sight-glass merely by the difference of its
specific gravity, as compared with water and then passes off through the
ducts provided to the parts to be lubricated.
For stationary engines the double connection is preferable, and should
always be connected to the live steam pipe above the throttle. The
discharge arm should always be long enough (4 to 6 inches) to insure the
oil magazine and condenser from getting too hot, otherwise it will not
condense fast enough to give continuous feed of oil. For traction or
road engines the single connection is used. These can be connected to
live steam pipe or directly to steam chest.
In a general way it may be stated that certain precaution must be taken
to insure the satisfactory operation of all sight-feed lubricators. Use
only the best of oil, one gallon of which is worth five gallons of cheap
stuff and do far better service, as inferior grades not only clog the
lubricator but chokes the ducts and blurs the sight-glass, etc., and the
refuse of such oil will accumulate in the cylinder sufficiently to cause
damage and loss of power, far exceeding the difference in cost of good
oil over the cheap grades.
After attaching a lubricator, all valves should be opened wide and live
steam blown through the outer vents for a few minutes to insure the
openings clean and free. Then follow the usual directions given with
all lubricators. Be particular in getting your lubricator attached so
it will stand perfectly plum, in order that the drop can pass up through
the glass without touching the sides, and keep the drop-nipple clean, be
particular to drain in cold weather.
Now, I am about to leave you alone with your engine, just as I have left
any number of young engineers after spending a day with them in the
field and on the road. And I never left one, that I had not already
made up my mind fully, as to what kind of an engineer he would make.